Taxonomy
Sars (1911b: 418) proposed the genus Leptomesochra Sars, 1911b to accommodate Mesochra macintoshi Scott & Scott, 1895b (incorrect original spelling “MacIntoshi”), Normanella attenuata A. Scott, 1896, and two new species Leptomesochra tenuicornis Sars, 1911b and L. confluens Sars, 1911c, but neglected type fixation. According to Lang (1936d: 134) L. confluens was sufficiently different from its congeners to exclude it from the genus Leptomesochra, an opinion that had already been voiced earlier by Gurney (1932: 50). Consequently, Lang (1936d: 135) proposed the genus Leptameira (type species by monotypy: Leptomesochra confluens) which remained monotypic until Nicholls (1939a: 282) added Leptameira attenuata Nicholls, 1939a. Lang’s (1936d: 134–135) superficial statement that “...Leptomesochra confluens Sars unterscheidet sich von den übrigen Arten im Bau des 1. Maxillipeden und des 5. Beinpaares und muß in eine besondere Gattung ... gestellt werden” does not satisfy the provisions of ICZN Art. 13.1.1. since no specific diagnostic characters were mentioned; consequently, it does not make the name Leptameira available. Conversely, Nicholls (1939a: 282) explicitly mentioned the fused rami in leg 5 as a differentiating character for Leptameira, however, since he refrained from type fixation, his paper also failed to make the generic name available. After having consulted Klie’s (1929: 359) previously unnoticed description of the male of Leptomesochra macintoshi (Scott & Scott, 1895b), Lang (1944: 24; 1948: 785) himself relegated Leptameira to a junior subjective synonym of Leptomesochra. He also added Leptomesochra infima Monard, 1928 to the latter genus but overlooked Nicholls’s (1939a) description of Leptameira attenuata. Lang’s (1948: 7, 839) inexplicit designation of the oldest originally included species, Mesochra macintoshi, as the type of Leptomesochra is invalid for reasons outlined above. The first author to have validly fixed the type is Vervoort (1964: 270) who cited Normanella attenuata A. Scott, 1896 as the type species. Vervoort (1964: 271) also included L. nasuta Sewell, 1940, L. africana Kunz, 1951, L. eulitoralis Noodt, 1952, L. elongata Boži , 1955, L. pygmaea Vervoort, 1964 and L. nichollsi Noodt, 1955a in the genus, the latter being a new substitute name for Leptomesochra attenuata (Nicholls, 1939a) (a secondary subjective homonym of L. attenuata (A. Scott, 1896) (cf. Noodt 1955a: 96). Lang (1965: 338) revised the genus Leptomesochra and subdivided it into three genera based on the endopodal segmentation of legs 3–4. In the genus Praeleptomesochra Lang, 1965 he grouped Leptomesochra africana (type by original designation) and Praeleptomesochra similis Lang, 1965, both of which display 3- segmented endopods in legs 3–4. He also referred Leptomesochra pygmaea to this genus in a postscript to his work (Lang 1965: 548). In the genus Leptomesochra he included species which exhibit 2-segmented endopods (Mesochra macintoshi, Leptomesochra nasuta, L. confluens, L. infima and Leptameira attenuata). Finally, in the genus Interleptomesochra Lang, 1965 he included species with a 2-segmented leg 3 endopod and a 3-segmented leg 4 endopod (Normanella attenuata, Leptomesochra tenuicornis, L. elongata, L. eulitoralis and Interleptomesochra reducta Lang, 1965) and fixed L. tenuicornis as the type species by original designation. However, the inclusion of N. attenuata in this genus effectively renders the generic name Interleptomesochra Lang, 1965 a junior subjective synonym of Leptomesochra. Hence, according to current ameirid systematics the generic concept of Leptomesochra Sars, 1911b in reality coincides with Lang’s (1965: 375) diagnosis of Interleptomesochra. In addition to the five species referred to this genus by Lang (1965) and which are listed above, Leptomesochra also includes two other species that were originally assigned to Interleptomesochra, i.e I. noodti Galhano, 1968 = Leptomesochra noodti (Galhano, 1968) comb. [details]